Our studies have concerned cystinosis, the metabolic errors of glutathione synthesis and degradation (glutathionuria, glutathione synthase deficiency and gamma glutamyl-cysteine synthase deficiency), glucose-6-phosphate dehydrogenase deficiency in which the capacity for glutathione reduction is decreased, homocystinuria, phenylketonuria, non-ketotic hyperglycinemia, galactosemia and adrenal leukodystrophy. We have been interested in the development of newer forms of treatment and diagnosis for a number of these metabolic disorders and in understanding the mechanisms of disease production and related normal processes. A number of specific treatments are under investigation. Animal models of human genetic diseases are studied. Investigations have also been undertaken to explore the possibility of transferring genetic material into cells with the use of lipochromosomes. The most important advances in the past year include discovery of the etiology of cystinosis and identification of the first transmembrane lysosomal transport system for amino acids.